The latest Nintendo consoles showed us that few key titles can reverse the destiny of the console (DS and 3DS). It's too early to declare the WiiU already dead or it'll do sub-GameCube numbers in LTD.
While that is true in theory, the DS and 3DS were not tracking nearly as badly as the WiiU is right now. Plus, the revivals in the handheld realm were much different landscapes when considering that third parties wanting to push handhelds didn't really have great alternatives (well, at least before the PSP hit its stride in Japan at least, and we all know about the Vita). With the WiiU, third parties can find other alternatives which seem to be paying off a lot better in the short term. With this in mind, the DS and 3DS at least got non-Nintendo support to somewhat sustain themselves while Nintendo got its ducks in a row, and this does not seem to be the case with the WiiU at the moment.